The present invention relates to a integrated circuit devices and a methods of manufacturing the same. More particularly, the present invention relates to integrated circuit devices having a stack structure and methods of manufacturing the same.
Generally, a material may be classified as a single-crystalline material, a polycrystalline material or an amorphous crystalline material based on the crystalline structure of the material. The single-crystalline material has one crystalline structure, the polycrystalline material has a plurality of crystalline structures, and the amorphous crystalline material has a structure having an irregular atom arrangement. As the polycrystalline material has a plurality of crystalline structures, the polycrystalline material may have many grain boundaries. When there are a large number of grain boundaries, carriers, such as electrons or holes, generally cannot move easily and cannot be efficiently controlled.
In manufacturing a system-on-chip (SOC) device or a semiconductor (integrated circuit) device that includes a thin-film transistor (TFT) having a stack structure, the single-crystalline silicon material is widely used as a layer for an active region.
A method of forming the single-crystalline layer will now be described. An insulating layer pattern having an opening is formed on a single-crystalline silicon substrate. A seed layer having a single-crystalline structure is formed in the opening by a selective epitaxial growth (SEG) process. A first amorphous crystalline silicon layer is formed on the insulating layer pattern including the seed layer. A laser beam is then used to irradiate the first amorphous crystalline silicon layer. As a result, the first amorphous crystalline silicon layer is changed into a first single-crystalline silicon layer by a phase change of the first amorphous crystalline silicon layer.
However, when the first single-crystalline silicon layer is formed by the above-mentioned method, as shown FIGS. 1A and 1B, defective portions may be formed in the first single-crystalline silicon layer. For example, when a laser-induced epitaxial growth (LEG) process is performed, defective portions having a protruded shape are typically formed.
When a second amorphous crystalline silicon layer on the first single-crystalline silicon layer having the defective portions is phase-changed by laser irradiation, the defective portions of the first single-crystalline silicon layer may be transcribed into the second amorphous crystalline silicon layer. As a result, a shape corresponding to a shape of the defective portions may be formed in the second single-crystalline silicon layer. Accordingly, when the defective portions are formed in the second single-crystalline silicon layer, the electrical reliability of the semiconductor device may be deteriorated.
As described above, a single-crystalline silicon layer formed by a conventional method may have deteriorated electrical characteristics due to the defective portions.